For NHS jobs and related university courses you will need to take a numeracy assessment. Use the ‘snap’ website (http://www.snap.nhs.uk/) to practise the skills needed. You will need to register at http://www.snap.nhs.uk/user/snap/register#prospective-user-table (choose the option prospective student/healthcare worker).
Wondering about a future involving Chemistry? Try this website for ideas: http://www.rsc.org/careers/future/